Many commercial and industrial sites are commonly classified as hazardous environments due to risk of explosion or fire. Areas involving fuel-dispensing equipment, for example, are classified as hazardous due to the types of products handled by these dispensers. A well-defined classification system for such hazardous environments has been developed, and equipment can be rated to operate in various environment classes. In one such system, areas where ignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors can exist under normal operating conditions and/or where hazard is caused by frequent maintenance or repair work or frequent equipment failure are classified as Class I, Division 1. One such environment is the inside of the hydraulic cabinet of a gasoline dispenser. In such environments, electronics are required to be “explosion proof” or “intrinsically safe,” meaning that they cannot create a spark capable of ignition even in the case of a fault of electronics.
Areas where ignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors are not normally present, but may exist due to an accidental rupture or breakdown, are classified as Class I, Division 2. This typically includes areas adjacent to Class I, Division 1 areas. The immediate area around a dispenser would be an example of such an area. Electronics used in this area are required to not be able to produce a spark capable of ignition under normal operating conditions.
The type of fuel dispensed determines the classification of the hazardous zones in and around the dispenser. Fuels with vapors that are heavier than air differ from those with properties that are lighter than air and thus create different zones. For example, CNG is lighter than gasoline/diesel vapor and behaves differently. As such, CNG dispensers must meet different (more stringent) safety requirements than, for example, gasoline or diesel dispensers.
Electronics must be designed to meet the requirements of the zone in which they will reside. In some cases this can be expensive (e.g., the design of Intrinsically Safe Barriers or Explosion-proof boxes) and, in still other cases, it may be difficult to design or protect the electronics so as to perform the desired function while meeting the zone requirements (e.g., the design of a receipt printer to be used in a Class I, Division 1 area).
Natural gas is considered to be a greener energy source than gasoline due to its lower emission profile. Its adaptation, however, has been relatively slow due to a lack of distribution network. Whereas gasoline stations are nearly ubiquitous, natural gas (e.g., CNG or Liquefied Natural Gas (LNG)) fueling stations are sparse. One reason for this is due to the high cost required to implement natural gas dispensers, which requires, for example, specially designed electronics as discussed above.
To avoid the high cost of electronics specially designed to meet the environment requirements, some current CNG dispensers are physically separated from dispensers of other fuels such as gasoline, diesel, or additives. Some current CNG dispensers exclude electronics, such as payment/media terminal. Some current CNG dispensers require venting around the electronic module, for example, at the payment terminal.
Accordingly, there remains a need for a dispenser system that can utilize cheaper electronics that are not specially designed for operation in a classified hazardous environment while being safely deployed in such an environment. There is also a need for a combined fuel dispensing system that can dispense more than one type of fuel.